The invention relates to driving belts, such as are used particularly as power and speed transmission elements on spindle mechanisms in the textile industry. Such driving belts are obtainable in the trade in various embodiments. These known types are described below.
Driving belts composed of cotton or plastic fibers, which are woven to a specific width and which are connected continuously by means of sewing or adhesive bonding, are traditionally in very common use. Moreover, driving belts of this type which are produced continuously to the particular dimensions ordered are also on the market. Driving belts cut out in strip form from web material with several fabric plies and joined together continuously are a further development. The advantage of these is that the belts can be cut out from the web material in the particular width desired, the ends being connected together by adhesive bonding. Finally, driving belts produced from plastic by extrusion are also known.
All these known driving belts have considerable disadvantages in view of the most important requirements of the textile industry, namely reliable handling, operating safety and energy savings in operation. Thus, the connections of the belt ends made by means of adhesives or by etching with solvents are insufficiently pliable and durable. Besides, these connecting processes, in all the high outlay, are somewhat harmful to health and are also not environmentally safe. Consequently, instead of adhesives, bonding sheets are inserted between the belt ends to be connected; but in this case a thickening and stiffening of the junction have to be accepted. Moreover, the use of bonding sheets is not economical.
On the other hand, although the driving belts woven to a specific width are very pliable and, if they are composed of cotton or similar fibers, also relatively heat-resistant, nevertheless during each pass of a spindle the ends of these driving belts bonded or sewn with an overlap exert an impact effect which is detrimental to the service life of the belt and to the spindle mounting. Moreover, these driving belts are not anti-static and therefore, because fiber fly adheres to them, lead to uncontrolled slipping and consequently to low efficiency.
With driving belts produced from web material with several fabric plies, a change was made with some success to the use of plastic fibers of high breaking strength as warp filaments and relatively heat-resistant fibers as weft filaments. It is also known to combine a fabric ply of plastic with one of cotton, an anti-static intermediate layer often being incorporated, in order to prevent fiber fly from adhering. However, these driving belts, because they are less pliable, require more drive power to operate them. Furthermore, this special multi-layer structure results in disadvantages, particularly as regards layer adhesion, the connection of the ends of the driving belt and fraying of the edges.
Continuously woven driving belts and those produced from plastics by extrusion have not been successful in capturing an appreciable share of the market. Where continuously woven driving belts are concerned, production and stock-keeping are not economical. As regards one-piece driving belts produced by extrusion, the requirements with respect to adhesive properties cannot be properly satisfied.